1. Field of the Invention
This invention relates to a press machine, and more particularly to a transfer device adapted to supply blanks to press-machining positions on a table of the press machine and deliver pressed articles therefrom.
2. Description of the Prior Art
Transfer devices for use in press machines which have so far been employed include a system in which a pair of drive units for transfer are mounted on both sides of the press machine body and one or two transfer bars are mounted between the pair of drive units, and another system in which drive units are mounted in front of the press machine body, the arrangement being made such that said drive units can oscillate at least one transfer arm. The above-mentioned system or arrangement, however, is disadvantageous in that the drive units and the transfer bars or the transfer arms stand in the way and make it difficult for the operator to make access to the dies mounted on a bolster, maintenance and inspection of the dies is troublesome to carry out and require a long time.
Further, there have been known a transfer device wherein a pair of feed bars provided with a plurality of clamp claws are arranged to make rectangular motion and those in which feed bars comprising a plurality of clamp members are adapted to move vertically and reciprocate longitudinally. However, in both the transfer devices, the length of feed is constant on the loading side and on the unloading side, respectively. Therefore, when the distance between the position of the blank on the loading side and the press machining position is longer than the distance between each of the press machining positions, it becomes necessary to provide an idle station on the loading side, thus increasing the time for the replacement of dies and also the cost thereof.
Further, in the conventional transfer devices for use in press machines, transfer members such as vacuum-cups or jaws or the like are fitted to a feed bar or feed bars adapted to make two-dimensional or three-dimensional motion by means of bolt or clamp means. In case of replacing the transfer member with a different one, it is required for the operator to replace manually the bolt or clamp means with new ones. Therefore, the replacement operation of the transfer member becomes very troublesome and requires a considerable time.